As used herein, the terms "corrugated", "convoluted" or "convolute" are used substantially interchangeably to describe known forms of plastic tubing having a surface formed with alternating ridges and grooves either on the tube outer surface, the inner surface or both. Such a corrugated or convoluted profile may be formed as a series of alternative ridges and grooves oriented in planes perpendicular to the tubular axis or as one or more helically extended ridges and grooves typically disposed at a small helical angle with respect to the tubular axis. In reference to helically extending ridges and grooves, each turn should be considered to mean a single ridge and groove in the specification and claims which follow.
Exemplary prior art tubes of the kind referred to are commonly used in the automotive industry where flexibility and the capability of protecting against abrasion are requisite properties. Typical of such products is the sleeve disclosed in U.S. Pat. No. 4,967,799 wherein an abrasion-resistant corrugated sleeve having a lengthwise slit is intended as an oversleeve for radiator hose in order to protect the radiator hose from wear caused by abrasion. For use in the protection of wiring harnesses, U.S. Pat. No. 4,970,351 provides a layer of sound deadening foam material to an axially slit corrugated tube for the purpose of eliminating rattles and unacceptable noise caused by vibration of the corrugated tube against other components in an engine compartment. The tubing disclosed in the '351 patent, while damping vibration from sources external to the tube, does not adequately protect against rattles and other vibrational noise caused by the vibration of the conductors themselves and tends to limit the tube's capacity to flex. Accordingly, a need has been recognized for tubing that provides adequate protection for bundles of wiring and other elongated substrates while effectively damping noise caused by sources external to the tubing, as well as noise caused by vibration of the wires or other substrates themselves.